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Briggs and Stratton Engine for my lawn mower won't start

Craig Parmenter's Avatar

Join Date: May 2013
Posts: 2

05-11-13, 04:37 PM   #1  
Briggs and Stratton Engine for my lawn mower won't start

Model 126T05-0856-B1
Engine is 2 years old and has been used no more than 40 times
I annually replace the oil, spark plug, and air filter so it has been done twice now.
It does not have a primer or a choke. It did not have stale gas sitting in it over the winter and it has fresh gas in it now.

I did my annual tune up last night on the mower, went to start it up and no go. Went out to try it again today still no go. I don't believe it's a clogged fuel line as gas appears to be getting to the spark plug. I've removed the air filter and tried to start it, still no go. It's full of brand new gas and new oil. I double checked and did not over fill the oil. The boot is not dirty, the plug gap is correct (.30). I've tried both the pull start and the electric start and it just doesn't fire. I've had trouble with this engine flooding if it doesn't stay level but usually let it rest 20 minutes and it will start fine.

I'm not sure what else to try and any other suggestions would help.
Thanks in advance!


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marbobj's Avatar

Join Date: May 2006
Posts: 3,659

05-11-13, 05:06 PM   #2  
Usually what you have is really common for the first start of the season. It has to do with gas residue in the combustion chamber.

First turn off the gas going to the carburetor or, if no shutoff, pinch the gas line shut or dump all the gas out of the gas tank. This keeps from feeding the flooded condition and making it worse. Then....

Put the throttle at full run position where you would have it for cutting heavy grass, take out the spark plug and turn the engine over about 5 to 10 times. Make sure the spark plug wire is away from anything that may serve to jump a spark.

Then put a teaspoon of gas directly into the spark plug hole and put the plug back put the spark plug back in it. Leave the throttle at full run and spin the engine over. It will likely try to start if you have a good spark and die after a few seconds.

Then open up the supply of gas to the carburetor and try to start it with the cold start procedure you have in the manual or that you normally use.

Craig Parmenter's Avatar

Join Date: May 2013
Posts: 2

05-12-13, 08:27 AM   #3  
Thank you very much. I tried this process and it didn't work. I got a couple of puffs of smoke with the teaspoon of gas but it never really fired. I filled half the tank up tried again and a couple of puffs of smoke and a couple of pops but never fired. Nothing on subsequent pulls.

I thought it may be a bad plug and I swapped that, still nothing.

Any other suggestions?

Thanks again,


cheese's Avatar
Forum Topic Moderator

Join Date: Jul 2001
Posts: 16,575

05-12-13, 11:38 AM   #4  
Sounds like it's flooded to me. Check the choke, I imagine it is closed and not opening when the engine starts. If you take the air filter and cover off and look into the carb, you can see the choke. Open it and see if it will run.

"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

helpman1234's Avatar

Join Date: Sep 2013
Posts: 1

09-25-13, 12:44 PM   #5  

I reviewed your inital thread. You set the spark plug gap to (.30) should it be (.030). let me know if the fix your problem?

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